Description of the Prior Art
It is the conventional practice to manually conduct visual inspection of containers during their production, processing or completion after filling, in order to detect defects and maintain quality inspection. In the recent years, in order to create labor savings or for automation as a means of overcoming labor shortage, it is the trend to install automatic inspection apparatus using video camera and an electronic processor to replace manual inspection.
As an example, bottles or the like formed by plastic or glass are widely used as the beverage containers. Often such containers break or leak due to improper processing during the manufacturing of the containers of their handling during transit. Carelessness in handling and mishaps during the manufacturing process of containers result in such damage to the containers that they create a defective condition during the subsequent filling process and/or the capping of the containers. Therefore, at the present time a large number of people are required to conduct visual inspection at the various stages, starting with the beverage container manufacturing, the container washing, filling, capping as well as the ultimate packaging. Accordingly, in order to replace the manual processing, the installation of automatic inspection apparatuses that utilize a video camera and an electronic processor has become the practice by which faulty containers are automatically rejected.
Such arrangements are not only needed for beverage containers, but also required during the production and filling of various other types of products.
One example of such above mentioned container or commodity inspection apparatus of the prior art is explained with reference with FIG. 1 to FIG. 3.
FIG. 1 schematically shows the structure of a container inspection apparatus in which a container made of transparent material such as glass, plastics or the like, is irradiated by a lighting device 2 such as a light source, i.e.: a lamp or the like. A light diffuser place 3 is placed between the lighting device 2 and container 1 in order to uniformly diffuse the light from light source 2. A video camera 4 used as an image sensor picks up the image of container 1, and passes the image to an electronic processor 5 which is composed of a computer or the like. A monitor M1, to which the output from the video camera 4 and the electronic processor 5 are supplied so that the respective windows 6 and 7.sub.1 -7.sub.4 are shaped and display thereon the image of container 1 as will be described later.
In this apparatus, the light passes through a transparent container 1 and is caught by the video camera 4, which video output is processed by electronic processor 5 so that the existence or not of defects on the container 1 is detected. For containers that are of an opaque nature the system will catch the reflected light and a similar inspection can be conducted.
The block diagram of FIG. 2 shows the composition and function of the electronic processor 5 in the inspection apparatus of the prior are, and the schematic diagram of FIG. 3 shows the positions of the respective image windows relative to the container 1. As shown in FIGS. 2 and 3, the output video signal of video camera 4, first provides a positioning window 6 set at the neck portion of container 1 and determines the center axis x--x of container 1 in the electronic processing circuit 6A. In other words, both side edges of the neck portion of container 1 is detected within window 6 from which edges the center axis x--x of container 1 is determined. The purpose in determining the center axis x--x is to accurately setup the positions of the remaining inspection windowns relative to container 1. In other words, when the container 1 is assumed to be of symmetrical shape with respect to the center axis x--x, the respective inspection windows can be setup to be also symmetrically shaped with respect to the center axis x--x of container 1.
The above mentioned inspection windows are shown in FIG. 2 and 3 by the numerals 7.sub.1, 7.sub.2, 7.sub.3 and 7.sub.4. If four inspection windows 7.sub.1 to 7.sub.4 are employed and the shapes of the respective inspection window 7.sub.1 to 7.sub.4 may be adjusted slightly to cope with any change in the shape of container 1. Further, variations in light transmission, due to the change in the diameter of the container 1 dependent on its position can be accommodated by varying the position and shape of the inspection windows 7.sub.1 to 7.sub.4 upon electronic processing. The existence of any defects in the container 1 observed within the four inspection windows 7.sub.1 to 7.sub.4 are simultaneously judged at a judgment processing circuit 7A.
The advantage of providing four inspection windows 7.sub.1 to 7.sub.4 for one container 1 lies in the fact that if there is any variance in the shape of container 1 such as (when the diameter of container 1 changes, or when the shape of its neck changes, etc), it will be easy to respond thereto by making a slight changes in the dimension of shape of only the corresponding windows 7.sub.1 to 7.sub.4. In order to respond to the changes of the light transmission due to the differences in the diameter of the container the respective windows 7.sub.1 to 7.sub.4 can be set up within the electronic processing with separate sensitives. When a design or literal arrangement of lines or the like exists on a part of container 1 (hereafter called a pattern) it is difficult to detect any defect therein and that area to be exempt from inspection.
In the inspection apparatus above described, there is generally no need to conduct inspection of the pattern 8 portion of container 1. However, such pattern referred to by the numeral 8 generally exists around the entire outer circumference of the container 1 body. In many cases such pattern 8 is formed only about half the circumference. In this case, it is necessary to judge the good or bad of the portions other than the pattern 8. By the conventional apparatuses, it was impossible to make this judgment.